Process of treating ores.



J. W. EMERSON.

PROCESS OF TREATING ORES. APPLICATION FILED FEE-19, 19 4.

@FFKQE JosEPH w. amansou, or sauna, cor-oaano.

PROCESS OF TREATING OBES.

. messes.

Specification of Letters Patent. Patented Feb, 2, 19 15..

Application filed Eebruary 19, 1914. Serial Ito. 819,768.

To all whom z't may concern:

Be it known that I, JOSEPH W. Emerson,

a citizen of the United States, residing at Ores, of which the-followingis a specification.

This invention relates to processes j of treating ores; and it comprisesav method of separating zinc'blende from heavy concen-' trates containinthe same wherein a layer or body of sai concentrates is submergedbeneath the surface of a body of an aqueous liquid under circumstancespermitt ng a slight gas-generating attack of said liquid,

or of components of the same, upon the blende without material attackupon other components of said concentrates, the amount of the attackupon the blende being merely such as will cause the -blende particles torise in such liquid above the general plane of such layer or body, andwherein the attacked buoyed blende particles are at once separated fromresidual heavier 1particles and from further action of such iquid; allas more fully hereinafter .set forth and as claimed.

In the treatment of ores containing-zinc blende by the ordinary methodsof ore concentration, considerable difliculty is experienced inobtaining-a clean separation of the blende from the'pyrites, quartz,etc, on

I the ordinary types of shaking tables and the like. The specificgravity of blende is not very far difi'erent from that of pyrites andthe twojdo not separate welt. .It has been proposed to treatconcentrates containing particles of blende, pyrites and the like inaii'acid bath in such manner as to cause an attack of the blendeparticles with liberation of gas suflicient to causes. flotation of theblende particles; to cause the blende particles to rise to the surfaceof the bath whence they can be floated away. Such processes however havenot been of practical utility attacking blende to an extent suflicientto cause it to float causes a relatively great loss of acid and of zinc.The evolution of sulfureted hydrogen means the solution of acorresponding amount of zinc, and a neutralization of. a correspondingamount of acid. The dissolved zinc and the neutraliz ed acid aresubstantially worthless. Furthermore. and particularly in the case ofnitric acid, any. strength of acid which Will cause an attack of zincblende sufficient to float it usually attacks pyrites or othercomponents of the concentrates to an extent suflicient to cause someflotation of these minerals also, thereby giving an impure product. Forthe stated reasons, these flotation methods have not gone into use toany substantial extent. I have discovered however that it is notnecessary to use such a far going attack upon the blende particles andthat a much slighter action may be usefully employed. I have found thatby submerging concentrates containing blende in a relatively slow actinacid liquid the first result of the attack 1s to cause the blendeparticles to rise a little above the general plane of the layer ofconcentrates in which they are contained; this being particularly thecase when the layer, as is advantageously the case, is a travelinglayer,'one in which there is more or less agitation of the particles.Under these conditions, the blende particles rise above the generalplane of the layer and there is also a peculiar action taking place inthat. the separating blende'particles tend to clump together intoaggregates or bodies which are readily mechanically removed. Ordinarily,I allow the'action to take place to such an extent that there is merelya slight clearance, say half an inch or so, between the rising blendeparticles and the body of other minerals below. At this time I removethe clumped zinc, ordinaril by means of a conveyer or collectingmec'anism of any suitable type, fromc'ontact with the acid liquid, and Ialso. remove :the residual heavy minerals allowed'to drain back to thebath. Under these conditions there is a very slight, and

negligible, attack of the acid on the zinc blende; with a similarlynegligible waste of acid'and of zinc; Nor are-the other minerals of theconcentrates affected. The attack-of acids and the like upon zinc blendeis preferential to their attack on most of the other materials likely tooccur in heavy concentrates and by operating under the describedconditions there is practically no action upon other materials while theaction upon the blende is. as stated, negligible.

, In the described operation the period of c'ontact of the concentrateswith the acid bath and the strength and temperature of such bath are, ina way, reciprocal factors.

" The weaker or the colderthe acid the longer must be the contact beforethe described rising of the blende occurs, and'vice'versa. I thereforecorrelateathe period of'exposure of the blende to the acid. bath withthe strength and temperature of such acidbath in -such a manner as-toproduce thedescribed rising. I do not produce any general flotation forthe reasons stated ante. I I

Any suitable type of apparatus may be employed in performing ,thedescribed process; but it isadva'ntageous to convey to perform theoperation in a-closed tank.

In a closed. tank the atmospheric pressure above the liquid and-materialtraveling through it may be somewhat reducedwhich. will allowthe risin of the blendeparticles with an even sma ler consumption ofacid and. of zinc. Operation may be at the ordinary temperatures. If theliquid is hot the strength of acid must be much reduced. With a hotliquid, however the development of water vapor cooperates with thedevelop- 'ment of sulfureted hydrogen in producing the rising efi'ect;z'...e.,' a somewhat weaker acid'may be em loyedand the waste of acidand of zinc t er'eby made even smaller. However operation at "theordinary tem: perature gives very good results. I i The concentrates-maycome from anyof the ordinary shaking tables or other devices but shouldbe as free as possible of calcite and other light minerals. Theconcentrates are best so fine grained that the particles of zinc blendeare substantially free of gangue. Very many strengths of acid may eemployed; it being always remembered that the stronger the acid or thehigher itstemperature the less is the period of contact with theconcentrates required to produce the differential risingof the blende.As stated, it is desired to make theblende only rise while leaving theother materials as a heavy layer. With strong acid or a long contactthere will always be more or less rising of pyrites. Any strength ofacid or time of contact suificient to cause an actual flotation of theblende particles will not only result in loss of acid and of zinc butalso in the production of. an impure product containing pyrites. With apro or control of conditions, the separationo blendefrom pyrites andquartz is clean and perfect; the blende particles being free of pyritesand quartz. With theproper amount of rising in the baththe blendeparticles clump together in a curiousmanner; a manner resemblin that ofelectrifiedparticles'in some other re ations. These clumps may be very feasily removed from the solution by mechanical-means suchas a bucketconveyer dipping in the bath and extending toa point A acid containingabout IO-per cent. ofacid to work well. Hydrochloric or nitric acid ofsimilar strength may also be-used. A useful. bath is produced bydissolving bleaching powder (chlorid of lime) in a cold-dilute.

solution of nitric acid; about 10 minds of bleaching powder in 20gallons 80 or (3., these strengths maybe much reduced. It is notnecessary to use free-acid since the same results can be obtained bygenerating'a littleacid, or gas developing chemical, in the solutionitself. For example, the-bath may be a solution of salt, sulfate ofsoda, etc.,, and anelectric current, either alternating or direct,passed through the liquid from suitable insoluble electrodes; such ascarbon pole pieces. Un-

.der the action of the current acid orchlorin is developed in the liquidand these will give a preferential attack on'the blende particlessufiicient to produce the described risvertical section, onez;;.of-,thev.-;manv embodiments of apparatu s elemjents .which-mav be used inthe perfo' nnane'e of the described .process. In th s showing,-element 1. is a hopper or'the like acting as a source of con; centrateslThe concentrates fallupombelt convever 2 looped over pulleysfi and 4 andr extending in ajdenending curve beneath the surface of an acid bathcontained in tank 5. The length of this belt and the degree of curvatureshould be as to allow a layer of concentrates to form and remainon itssure A face duringitsperiodof traveh. In. passing f'. ;10 per 90 cent.nitric acid. I: the bathvbe'vheated to.

through the acid bath in this tank the blende is slowly acted on andtends to rise to form clumps which are scooped out by buckets 6 on belt7 and removed. The adhering acid drains back into the bath. The blendeis delivered by the scoops into a suitable place of storage or the like(not shown). It may be here washed or simply dried, this depending uponthe particular acid used. The

separated pyrites, quartz, etc., on the belt conveyer are removed "byscraper 8 and may be dumped into centrifugal 9 where the adhering liquidis removed and sent back a the bath through conduit 10. The separatedpyrites may be washed and the washing reconcentrated and added to thebath, if so desired. Where the electric current is employed, the tank orother vessel (5) employed may be of steel or other metal and connectedto source ofcurrent 11, a carbon rod or the like 12 acting as the otherelec-' trode.

What I claim is:

1. The process of separating blende from blende-containing concentrateswhich comprises submerging a layer of the concentrates in a substantialbody of an acid solution for a brief period of time, the strength andcharacter of the acid and the time ofcontact being so correlated as tocause development-of merely enough gas on the blende particles to causea lifting of such particles in such solution out of the general plane ofthe layer and a clumping together of such particles, and then engagingsaid particles before they reach the surface .and immediately removingthem from the acid solution.

2. Theprocess of removing blende from blende-containing concentrateswhich comprises submerging a body of such concentrates in a relativelydeep body of an acid solution, mechanically engaging said particles assoon as they rise above the general plane of such body of concentratesand immediately removing them from the acid solution.

3. The process of removing blende from blende-containing concentratesWhich comprises passing a shallow traveling layerof such concentratesinto and through an aqueous bath under circumstances causing apreferential gas-evolving attack upon the blende to an extent onlysufiicient to lift the blende particles slightly above the surface ofthe layer in clumped aggregates and at once mechanically engaging andremoving the lifted blende aggregates from the bath.

4. The process of removing blende from blende-containing concentrateswhich comprises passing a shallow traveling layer of such concentratesinto and through an acid aqueous bath, the strength of acid being suchas will cause an attack of the blende particles to an extent onlysufiicient to cause a lifting. of the same as clumped aggregates justabovesuch layer and at once mechanically engaging "and removing thelifted blende aggregates from the bath.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

JOSEPH W. EMERSON. Witnesses:

EMERSON, C. F. Johnson-

